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Give a rough estimate (by rounding off to nearest hundreds) and also a closer estimate (by rounding off to nearest tens):
(a) 439 + 334 + 4317 (b) 108734 - 47599 (c) 8325 - 491 (d) 489348 - 48365.
Make four more such examples.

Solution:

We will be using the concept of estimation in math to solve this problem.

(a) 439 + 334 + 4317

Round off of 439 to nearest hundreds = 400
Round off of 334 to nearest hundreds = 300
Round off of 4317 to nearest hundreds = 5000
Sum of 439 + 334 + 4317 = 400 + 300 +4300 = 5000

Rounding off to nearest tens

Rounding off to nearest ten of 439 = 440
Rounding off to nearest ten of 334 = 330
Rounding off to nearest ten of 4317 = 4320
Sum of (439 + 334 + 4317) to nearest ten = 440 + 330 + 4320 = 5090

(b) 108734 - 47599

Round off of 108734 to nearest hundreds = 108700
Round off of 47599 to nearest hundreds = 47600
Difference of (108734 - 47599) to nearest hundreds = 108700 - 47600 = 61100

Rounding off to nearest tens

Rounding off to nearest ten of 108734 = 108730
Rounding off to nearest ten of 47599 = 47600
Rounding off to nearest ten of difference of (108734 - 47599) = 108730 - 47600 = 61130

(c) 8325 - 491

Round off to nearest hundreds is (8325 - 491) = (8300 - 500) = 7800
On rounding off to nearest tens we get (8325 - 491) = 8330 - 490 = 784

(d) 489348 - 48365

Round off to nearest hundreds is (489348 - 48365) = 489300 - 48400 = 440900
On rounding off to nearest tens we get (489348 - 48365) = 489350 - 48370 = 440980

Four more examples are as follows
(i) 4856 + 661
Rounding off to nearest hundreds
4856 + 661 = 4800 + 700 = 5500
Rounding off to nearest tens
4856 + 661 = 4850 + 660 = 5510

(ii) 772 - 389
ounding off to nearest hundreds
772 - 389 = 800 - 400 = 400
Rounding off to nearest tens
772 - 389 = 780 - 390 = 390

(iii) 6365 - 2865
Rounding off to nearest hundreds
6365 - 2865 = 6400 - 2900 = 3500
Rounding off to nearest tens
6365 - 2865 = 6370 - 2870 = 3500

(iv) 8245 - 6313
Rounding off to nearest hundreds
8245 - 6313 = 8200 - 6300
= 1900
Rounding off to nearest tens
8245 - 6313 = 8240 - 6310
= 1930

NCERT Solutions Class 6 Maths Chapter 1 Exercise 1.3 Question 2

Give a rough estimate (by rounding off to nearest hundreds) and also a closer estimate (by rounding off to nearest tens):(a) 439 + 334 + 4317 (b) 108734 - 47599 (c) 8325 - 491 (d) 489348 - 48365. Make four more such examples

Summary:

(a) 439 + 334 + 4317 c rounded off to nearest ten = 440 + 330 + 4320 = 5090 (b) 108734 - 47599  rounded off to nearest ten = 108730 - 47600 = 61130 (c) 8325 - 491  rounded off to nearest ten = 8330 - 490 = 784 (d) 489348 - 48365 rounded off to nearest ten = 489350 - 48370 = 440980

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